1. Field of the Invention
The present invention relates to an image processing apparatus which performs predetermined image processing on an image and an image processing program storage medium containing an image processing program which makes a computer operate as such an image processing apparatus.
2. Description of the Related Art
Recently, the field of printing has been computerize and it has become common practice for an editor to edit an image to be printed, using an editing computer, check layout of characters, photographs, and the like in the image, and use image data of the final image as a source document. In this type of printing, finishing touches are put to the image to be printed through image processing performed on the image at the data level. Finished quality of the printed matter depends heavily on conditions of paper surfaces such as whether the surfaces of the paper used for printing are coated. Thus, image processing in printing takes the conditions of paper surfaces into consideration.
In the field of printing, it is often the practice to use duplex printing which involves printing images on both sides of paper. Some paper differs in surface conditions between the front and back sides: for example, the front side is coated while the back side is uncoated. On the other hand, in a series of printing operations (a printing job) for a pamphlet, for example, all images are commonly subjected to the same type of image processing in most cases. The image processing includes a color conversion process which consists of adjusting image colors at the data level in order to obtain desirable image colors in printed matter. Thus, in duplex printing, the use of common image processing, i.e., a common color conversion process, for image data for the front and back sides just because the processing is performed in the same job may result in printed matter which differs in coloration between the front and back sides of paper when images are printed. Techniques have been proposed to deal with this situation, including those which regard printing on the front side and printing on the back side as separate jobs, separately perform image processing for the front side by reflecting conditions of the front side and image processing for the back side by reflecting conditions of the back side, and thereby obtain desirable printed matter with images adjusted to desirable coloration on both front and back sides (see, for example, Japanese Patent Laid-Open No. 2004-199292).
Also, it is known that paper often contracts or expands when images are printed on it by an image forming apparatus such as a printer. Such deformation of paper during printing can cause images on the printed matter to contract or expand together with the paper, resulting in distorted images. To deal with this situation, it is conceivable to learn, in advance, a degree of paper expansion/contraction (expansion/contraction rate) which is likely to occur during printing, estimate image distortion resulting from paper deformation during printing based on the expansion/contraction rate, cancel out the estimated distortion by performing a correction process such as expansion or contraction of the images during data-based image processing of the images to be printed on the paper, and thereby correct image distortion caused by paper deformation during actual printing. The paper deformation during printing depends heavily on conditions of paper surfaces such as whether the paper surfaces on which images are to be printed are coated. Thus, in the case of duplex printing on paper whose front and back sides differ from each other in conditions, the use of common image processing, i.e., a common correction process, for image data for the front and back sides can cause distortion to be corrected differently between the front and back sides. Techniques have been proposed to deal with this situation, including those which separately perform image processing for the front side to correct image distortion on the front side and image processing for the back side to correct image distortion on the back side and thereby obtain desirable printed matter with image distortion corrected identically on the front and back sides (see, for example, Japanese Patent Laid-Open No. 2004-54902).
Even in the case of simplex printing, if multiple types of paper are used in a single job, conditions of paper surfaces may vary among images such as paper surfaces for some images are coated while paper surfaces for other images are uncoated. Thus, the use of common image processing including a color conversion process and correction process for all the image data may result in differences in finish among different pieces of printed matter. To deal with this situation, a technique has been proposed which treats preparation of each piece of printed matter as an independent job, perform image processing independently for each piece of printed matter according to the type of paper used for the given piece of printed matter, and thereby obtain multiple pieces of printed matter with preferably finished images.
However, with the above techniques, to give desirable finish to all the images in printed matter produced by duplex printing or by printing on multiple types of paper, the pamphlet designer must set a job for each image by knowing conditions of the paper surface on which the image on each page will be printed. This is troublesome and imposes a great burden on the designer.